Oil-soluble copolymers of acrylic acid esters and quaternary ammonium salts of acrylic acids



United States Patent Ofitice 3,225,373 Patented Dec. 28, 1965 OIL-SOLUBLE POLYMERS 0F ACRYLIC AID ESTERS AND QUATERNARY AMMONIUM SALTS 0F ACRYLIC ACIDS Elizabeth L. Fareri and John R Pellegrini, In, Pittsburgh,

Pa., assignors to Gulf Research 5; Development Company, Pittsburgh, Pin, a corporation of Delaware No Drawing. Filed Dec. 28, 1959, Ser. No. 862,056

11 Claims. (Cl. 260--86.1)

This invention relates to certain novel, oil-soluble nitrogenous copolymers and more particularly to copolymers of higher alkyl esters of acrylic or methacrylic acid and long-chain N-substituted quaternary ammonium salts of acrylic or methacrylic acid and to lubricants containing these copolymers.

Lubricants for many present-day internal combustion engines are required not only to lubricate and to cool engine parts, but also to maintain the engine parts contacted by the lubricant in clean condition. Uncompounded lubricating oils are frequently found to be less than fully satisfactory with respect to the last-mentioned function, especially under severe operating conditions, in that they permit buildup of carbonaceous deposits that result in part from deterioration of the oil itself, but that result principally from fuel combustion products. These deposits interfere with proper engine functioning. In order to improve the ability of oils to maintain an engine in clean condition, a wide variety of metal-organic compounds (principally alkaline earth metal salts), such as salts of substituted phenols and petroleum sulfonic acids, salicylates, thiophosphoric acids, and carboxylic acids have been proposed. Unfortunately, metal-organic detergents themselves tend to form still other deposits, that is, combustion ash deposits, in the combustion chambers of internal combustion engines upon combustion of oils containing such metal-organic addition agents. Also, the increased corrosionof copper-lead and cadmium-silver bearings that frequently accompanies the use of detergents has been attributed to the cleansing action of detergents, which prevents deposition on the bearings of acidresistant, protective lacquer deposits.

It has also been proposed to overcome viscosity deficiencies in uncompounded lubricating oils at high temperatures by incorporating therein small proportions of viscosity index improvers comprising oil-soluble, nonmetallic organic polymeric materials. By means of these materials the viscosity of lubricating oils can be maintained relatively constant notwithstanding increases in temperature. However, typical commercial viscosity index improvement agents exhibit little or no cleansing ability in lubricating oils. 7

We have now found that the detergent properties of hydrocarbon oil lubricants, as well as the viscosity, viscosity index, and bearing corrosion inhibiting properties, can be improved by incorporating therein a small proportion of an ashless, that is nonmetal-lie, copolymer of (a) a monomeric alkyl ester of acrylic or methacrylic acid whose alkyl substituent contains 8 to 18 and preferably 12 to 18 carbon atoms, and (b) a monomeric quaternary ammonium salt of acrylic acid or methacrylic acid, one of whose four covalent N-bonds is attached to a monovalent aliphatic hydrocarbon radical containing 8 to 18 and preferably 12 to 18 carbon atoms, two other of whose covalent N-bonds are attached to monovalent aliphatic hydrocarbon radicals containing 1 to 18 carbon atoms, or aralkyl radicals containing 7 to 23 carbon atoms, and whose remaining covalent N-bond is attached to an alkyl group containing 1 to 4 carbon atoms. The quaternary ammonium salt monomers and the ester monomers that form the copolymers disclosed herein are preferably copolymerized in ratios of about 0.05 to 0.75 :1 by weight, but other ratios can be used. For example, ratios in the range of 0.03:1 to 1:1 can be used. Polymers prepared from the above-indicatcd monomer, ratios will usually be characterized by a nitrogen content in the range of 0.04 to 3.0 percent by weight. We normally prefer to employ copolymers containing at-least about 0.2 percent and preferably about 0.2 to 2 percent nitrogen, but copolymers of greater and lesser nitrogen content can be used. Specific examples of copolymers included by this invention and with which excellent results can be obtained are the 1:9 and the 0.711 weight ratio copolymers of monomeric distearyldimethylammonium methacrylate and monomeric lauryl methacrylate, the 1:9 weight ratio copolymer of stearylt-rimethylammonium methacrylate and lauryl methacrylate. Examples of other copolymers included by the invention are the 1:9 weight ratio c0- polymer of tri(caprylyldecyl)methylammonium methacrylate and lauryl methacrylate and the 0.05 :1, the 0.1:1, the 05:1, and the 1:1 weight ratio copolymers of monomeric dioctadecenyldimethylammonium, octadecenyldimethyle-thylammonium, octadecenyltrimethylammonium, lauryltrimethylammonium, distearyldimethylammonium, dilauryldimethylammonium, dihexadecyldimethylammonium, hexadecyltrimethylammonium, oc-tadecyltrimethylammonium, laurylbenzyldimethylammonium, lauryldimethyl(ethylbenzyl)ammonium, and lauryl(1nethylbenzyl)dimethylammonium acrylates and methacrylates, and monomeric n-octyl, lauryl, oxo-octyl, 2-ethylhexyl, oxotridccyl, and n-hexadecyl acrylates and me-thacrylates. We prefer to employ the copolymers in hydrocarbon oil lubricants in proportions of 0.5 to 5 percent by weight but other proportions can be used. For example, the copolymers can be employed in amounts of 0.1 to 10 percent by weight with good results. i

The preferred ester monomers from which the copolymers of this invention are prepared can be represented by the general formula: CHFCRCOOR where R is hydrogen or a methyl radical, and R is a straightor branched-chain alkyl group containing 12 to 18 carbon atoms, such as lauryl, oxo-tridecyl, n-hexadecyl, or noctadecyl.

The preferred quaternary ammonium salt monomers from which the herein described copolymers are prepared can be represented by the general formula:

I! CH2=CRCOON R/II nil/I Where R is as defined above, R is an alkyl, alkenyl, or alkadienyl radical containing 12 to 18 carbon atoms, such as lauryl myristyl, n-hexadecyl, n-octadecyl, noct-adecenyl, or n-octadecadienyl, R" and R are radicals of the same kind as R or alkyl radicals containing 1 to 4 carbon atoms such as rnethyl, et'hyl, propyl, 'butyl, or a mononuclear aralkyl radical containing 7 to 23 carbon atoms, such as benzyl, tolylethyl, or a polypropylated aralkyl radical such as p-tetraisopropylbenzyl, and R" is an alkyl radical containing 1 to 4 carbon atoms.

Neither the alkyl ester substituents of the ester monomers nor the long-chain groups attached to the covalent N-bonds of the quaternary ammonium monomers need be pure; instead these substituents can comprise mixtures of radicals derived from commercially available materials. For example, the alkyl ester substituents of the ester monomers can be derived from a mixture of synthetically produced, isomeric, branched-chain alcohols such as is produced by the well-known oxosynthesis process. Alternatively, the ester substituents can be derived from a mixture of fatty alcohols obtained from coconut oil fatty acids or tallow fatty acids or other acids derived from naturaliy occurring fats or oils. Similarly, the longchain groups attached to the covalent Nbonds of the nitrogenous monomer can comprise a mixture of alkyl, alkenyl, and/or alkadienyl groups derived from commercial materials such as coconut oil fatty acids, :soya fatty acids, or tallow fatty acids. When the substituents referred to above are derived from natural fats and oils, the mixed radicals will comprise homologous mixtures of alkyl, or alkyl and alkenyl, or alkyl, alkenyl, and alkedienyl radicals containing an even number of carbon atoms from 8 to 18. flThe ester substituents of the ester monomer and the N-substituents attached to the covalent N-bonds of the iitrogenous monomer can also be substituted, if desired, with nonhydrocarbon substituents such as halogens, hydroxyl, sulfhydryl, carbonyl, or the like that do no adversely affect the oil-solubility or detergent characteristics of the salts.

The preferred copolymers of this invention are copolymers of the above-indicated preferred monomers in weight ratios in the range of about 0.05 to 0.75 part by weight of quaternary ammonium salt monomer to 1 part by weight ester monomer.

The copolymers included by this invention can be prepared in any suitable Way. Thus, the copolymers can be prepared from the corresponding monomers with a diluent such as water in a heterogeneous system (usually referred to as emulsion or suspension polymerization), or With a diluent such as toluene, benzene, ethyl acetate, butyl acetate, ethylene dichloride, or methyl isobutyl ketone in a homogeneous system (usually referred to as solution polymerization). Solution polymerization in toluene or a solvent having similar chain transfer activity is the preferred method used in forming the copolymers disclosed herein, as this method and solvent produce a preferred class of copolymers characterized by a relatively high molecular weight.

copolymerization of the herein described monomers takes place readily under the influence of heat, light, and/or catalysts. Peroxide-type free radical catalysts, such as benzoyl peroxide, lauroyl peroxide, or t-butyl hydroper oxide, azo-type, free radical catalysts such as alpha,

'alpha-azodii-sobutyronitrile, and anionic catalysts such 'as metallic sodium in liquid ammonia, are examples of catalysts that can be used. The catalysts are normally employed in catalytic proportions, that is, from a few 'hundredths percent up to one or two percent by Weight of the monomers. Preferably, the catalyst is employed in proportions of about 0.2-1.0 percent.

copolymerization of the herein disclosed monomers can be effected over a wide range of temperatures, depending upon the particular catalyst and monomers chosen. For example, when using metallic sodium in liquid ammonia as a catalyst, copolymerization can take place at temperatures as low as 75 C. or lower. On the other hand, when alpha, alpha-azodiisobutyronitrile is used as a catalyst, as is preferred, temperatures ranging from ambient atmospheric temperature (approximately 25 C.) to about 150 C. can be used. Temperatures in the lower part of this range are preferred as such temperatures tend to favor formation of higher molecular Weight copolymers.

The copolymerization reaction is preferably carried out to substantial completion, that is, until the rate of formation of larger polymers has declined substantially. Substantial completion of the reaction can be judged by periodic sampling of the reaction mixture and by determination of the viscosity of the samples, the viscosity being an index of molecular weight. Although for best results it is preferred to carry out the reaction to substantial completion, this is not absolutely necessary. It is sulficient merely to allow copolymerization to proceed until the viscosity of a hydrocarbon lubricating oil containing the reaction mixture in detergent proportions will be appreciably increased. The time required to reach any given stage of polymerization can differ somewhat depending on the particular reaction conditions and upon the monomers employed. By way of example, good results have been obtained with times of polymerization in the range of about 3 to 35 hours.

Although copolymerization can be effected in contact with the atmosphere, a more desirable group or" copolymers, having relatively higher viscosities and molecular weights, can be obtained by carrying out the polymerization in the absence of oxygen. This can be achieved, for example, by blankcting the reaction mixture with an inert gas, such as nitrogen.

The average molecular weight of the copolymers disclosed herein Will normally be greater than about 2,000, and is preferably greater than about 7,500, as determined by conventional test methods. Usually, the molecular weights will not exceed about 500,000, but in some instances the molecular weights of the copolymers can be greater. In fact, copolymers having molecular Weights of any upper limit can be used, provided such molecular weight is not so great as to render the copolymers insoluble in hydrocarbon oils. The molecular size of the copolymers described herein is affected to some extent by the type of diluent, the monomerzdiluent ratio, the type of catalyst, the catalystzmonomer ratio, and the reaction temperature employed during copolymerization. The desired molecular size and copolymer yields can usually be adjusted Within the limits indicated above to produce the desired results. Thus, excellent results for the purposes of the present invention can be obtained by copolymerization of the herein disclosed monomers in an equal weight of solvent comprising equal proportions of toluene and a hydrocarbon lubricating oil using 0.15 to 0.6 percent alpha, alpha-azodiisobutyronitrile as catalyst at temperatures in the range of 60 to C. over a period in the range of three to seven hours.

It is important for the purposes of this invention that the copolymers be prepared directly from the monomers rather than by indirect methods, as the copolymers obtained by direct copolymerization of monomers are chemically and functionally distinct and different from copolymers prepared by indirect methods, at least partly by reason of their more uniform and more controlled composition.

The copolymers described herein can be incorporated in a wide variety of hydrocarbon lubricating oils. For example, the copolymers can be added to lubricating oils that have been derived from paraflinic, naphthenic, or mixed base crude petroleum oils, and that have been subjected to solvent or sulfuric-acid treatment, aluminum chloride treatment, hydrogenation and/or other refining treatments. 7

The herein described copolymers can be incorporated in the hydrocarbon oils in any convenient way. Thus, the copolymers as such can be added directly to the oils, in the form of concentrated solutions in solvents such as kerosene or light lubricating oil in order to facilitate blending. If desired, the concentrated solution also can contain other compatible addition agents designed to improve one or more properties of the oil. In the case of blended lubricating oils, the herein disclosed copolymers can be added to one of the component oils prior to blending. Some stirring, possibly with mild heating, may be desirable to facilitate more rapid formation of a homogeneous mixture, but this is not absolutely essential The herein disclosed copolymers can be added to the hydrocarbon lubricants in amounts sufficient to improve the detergency characteristics of the oils. The minimum and optimum effective proportions can vary somewhat according to the nature of the particular copolymer, which are not necessarily equivalent in effectiveness to each other. However, an appreciable improvement will usually be obtained by the use in lubricants of as little as 0.1 percent of the copolymers described herein. A major improvement will normally be obtained by the use of 0.5 to 5 percent of the copolymers, and such proportions are normally preferred. However, in the case of oils requiring relatively greater detergent characteristics, as much as percent or more of the copolymers can be used. The use of the herein described copolymers in proportions surficient to improve the detergency of the oils is ordinarily accompanied by an increase in the viscosity index of the oil and in the bearing corrosion inhibiting characterstics of the oil.

The copolymers of this invention and their preparation are further illustrated by the following specific examples.

Example I A mixture of di(hydrogenated taliow-alkyl)-dirnethylammonium chloride with an equal weight of methanol is warmed to 53 C. to dissolve the quaternary ammonium chloride. The active components of the resulting solution comprise about 75 percent dioctadecyldimethylammonium chloride, 24 percent dihexadecyldimethylammonium chloride, and 1 percent dioctadecenyh dimethylammonium chloride. To this solution there is added with stirring a methanolic solution of potassium hydroxide in a proportion equivalent to the quaternary ammonium chloride. Stirring is continued until the reaction temperature drops to 31 C. Potassium chloride is removed by suction-filtration. The filtrate comprises a methanolic solution of a quaternary ammonium hy droxide whose covalent N-substituents correspond to those of the original quaternary ammonium chloride. To the methanolic solution of the quaternary ammonium hydroxide there is added a five percent molar excess of glacial methacrylic acid. This reaction is exothermic and the temperature is kept below 30 C. by controlling the rate of addition of acid and/or by cooling as required. Methanol is removed at reduced pressure. The residue comprises chiefly dioctadecyldimethylammonium methacrylate, together with lesser proportions of dihexadecyldimethylammonium methacrylate and dioctadecenyldimethylammonium methacrylate.

To 20 grams of the dioctadecyldimethylammonium methacrylate prepared as indicated above there is added 180 grams of lauryl methacrylate, 100 grams of toluene, 100.5 grams of .a hydrogenated SAE 20W/ 30 lubricating oil, and 0.5 gram of alpha,alpha'-azodiisobutyronitrile. The reaction mixture is stirred and heated at 72-82 C. for about minutes. An additional 0.5 gram of alphaalpha-azodiisobutyronitrile is then added. Stirring and heating are continued at 82-90 C. for 1% hours, then at 7076 C. for 2% hours. Toluene is then removed at reduced pressure with heating. The product is an oil solution containing 66.7 percent by weight of a copolymer, hereinafter referred to as Copolymer 1, of the quaternary ammonium methacrylate (chiefly dioctadecyldimethylarnrnonium methacrylate) and lauryl methacryh ate in a 1:9 weight ratio. The weight of the oil concentrate prepared in accordance with this procedure is 304.9 grams. The Copolymer 1 concentrate prepared as described had the following characteristics:

A similar copolymer prepared in toluene from the same monomers in the same weight ratio had :an intrinsic viscosity at 77 F. in toluene of 0.44 deciliter per gram and a molecular weight of 190,000 as determined by the shear method of P. Bueche and S. W. Harding, Journal of Polymer Science, vol. XXXII, pages 177-186 (1958),

with application of an appropriate instrument calibration constant.

Example II To 125; grams of the mixed quaternary ammonium methacrylates prepared as described in the preceding example there is added 150 grams of hydrogenated SAE 20W/30 lubricating oil, 177.4 grams of lauryl methacrylate, 118.6 grams of toluene and 0.5 gram of alpha, alpha-azodiisobutyronitrile. The reaction mixture is not initially homogeneous. Polymerization is carried out under an atmosphere of nitrogen with stirring and heating at 60 to 73 C. for 6% hours, during which period the reaction mixture becomes homogeneous and more viscous than in the preceding example. Toluene in the amount of 78.4 grams is removed from the mixture under reduced pressure, the balance of the toluene being left in the mixture to avoid excessive foaming. The resulting product is then diluted with an additional 152.2 grams of the hydrogenated SAE 20W/30 oil, but it remains extremely viscous. This product, approximately 595.3 grams in amount, comprises a solution of lubricating oil and toluene containing 47 percent of a copolymer, hereinafter referred to as Copolymer 2, of the quaternary ammonium methacrylate (chiefly dioctadecyldimethylammonium methacrylate) and lauryl methacrylate in a 0.71:1 weight ratio.

Example III To the 32.2 gram residue obtained by evaporating under reduced pressure 50.4 grams of an isopropanol solution of "soya-trimethylammonium hydroxidea material comprising a mixture of 10 percent octadecyltrimethylamrnonium hydroxide, 35 percent octadecenyltrimethylammonium hydroxide, 45 percent octadecadienyltrimethylammonium hydroxide and 10 percent hexadecyltrimethylarnmonium hydroxide-there is added 0.1 mole (8.7 grams) of glacial methacrylic acid. Solvent and water of reaction are removed by evaporation under reduced pressure with mild heating. To 40.9 grams of the residue, soya"-trirnethylammonium methacrylate, there is added 360.0 grams of lauryl methacrylate, 200 grams of toluene and 2.0 grams of alpha,alpha-azodiisobutyronitrile. The reaction mixture is stirred and heated at 6370 C. for 5% hours. Nitrogen is bubbled into the reaction mixture throughout the reaction period. The viscous toluene concentrate is dissolved in 803.0 grams of a highly refined, parafiinic SAE 10W motor oil base, and toluene is removed by evaporation under reduced pressurewith heating to a maximum of 64 C. The highly viscous oil solution obtained has a Weight of 1203.7 grams and contains 33 /3 percent by weight of a 1:9 weight ratio copolymer, hereinafter referred to as Copolymer 3, of a mixture of stearyl-, oleyl-, linoleyland palmityltrimethylammonium methacrylates and lauryl methacrylate. Copolymer 3 concentrate, prepared as described, has the following characteristics:

Nitrogen, percent 0.11 Neutralization Value: ASTM D664-58 Total Acid Number 2.04 Total Base Number 3.51 Saponification Number: ASTM D94-56T 4.21

A similar copolymer prepared in toluene from the same monomers in the same weight ratio had an intrinsic viscosity at 77 F. in toluene of 0.25 deciliter per gram.

Example IV A solution of 135.8 grams tri(mixed caprylyldecyl)methylammonium chloride, having an average molecular weight of 442, in grams of isopropanol is warmed to 42 C. and reacted with an equivalent amount of potassium hydroxide (20.4 grams) in grams: of isopropanol. Potassium chloride is removed by filtration, and a portion of the solvent is removed from the filtrate by evaporation under partial vacuum with slight heating. The isopropanolic residue has a neutralization number of 92.8. To 36.3 grams of this residue (0.06 mole) there is added 5.4 grams (0.06 mole) of glacial methacrylic acid. Solvent is removed under reduced pressure with slight heating. The residue comprises 29.0 grams of tri(mixed caprylyldecyl)methylammonium .methacrylate.

To 25.0 grams of this residue there is added 225.0 grams of lauryl methacrylate, 500.0 grams of a highly refined, highly paraflinic SAE W lubricating oil base and 1.5 grams of alpha,alpha-'1zodiisobutyronitrile. The reaction mixture is stirred and heated at 7479 C. for 6% hours, nitrogen gas being bubbled into the reaction mixture throughout this period. The product is a moderately viscous oil solution containing 33 /3 weight percent of a 1:9 weight ratio .eopolymer, hereinafter referred to as C'opolymer 4, of tri(caprylyldecyl)methylammonium methacrylate and lauryl methacrylate. The copolymer concentrate prepared in this manner has the following characteristics:

Nitrogen, percent 0.14

Neutralization Value: ASTM D664-58 Total Acid Number 2.62 Total Base Number 3.74

Saponification Number: ASTM D9456T 18.46

Example V A solution of grams of cocoalkyl-benzyldimethylammonium chloride, having an average molecular Weight of 367, in grams of isopropanol is warmed to 40 C. and reacted with a solution of 4.5 grams (0.068 mole, assay percent) potassium hydroxide in 25 grams of isopropanol. The c-ocoalkyl radical is the mixture of C alkyl radicals (chiefly C alkyl) derived from coconut oil fatty acids. Potassium chloride is removed by suction-filtration. The filtrate, an isopropanol solution of alkylbenzyldimethylammonium hydroxide, is reacted with an equivalent quantity of glacial acrylic acid (0.068 mole, 4.9 grams). Isopropanol is removed under reduced atmospheric pressure. The residue consists essentially of C alkylbenzyldimethylammonium acrylate. To 25.0 grams of this material there is added 225.0 grams of lauryl acrylate, grams of toluene and 1.5 grams of alpha,alpha'-azodiisobutyronitrile. The reaction mixture is heated with stirring at 6570 C. for six hours, nitrogen being bubbled into the reaction mixture throughout the reaction period. The toluene concentrate is dissolved in 500.0 grams of a highly refined, highly parafiinic SAE 10W motor oil base, and toluene is removed under reduced atmospheric pressure with heating. The product is an oil solution containing 33% percent by weight of a 119 Weight ratio copolymer of C 'alkylbenzyltrimethylammonium acrylate and lau-ryl acrylate. The nitrogen content of a product obtained as described, calculated on an oil-free basis, is 0.50 percent by weight.

The foregoing examples are illustrative only and similar products can be obtained by the use in the foregoing examples of other monomer proportions disclosed herein, other quaternary ammonium methacrylates and acrylates, and other alkyl acry-la-tes and methacrylates disclosed herein. For example, there can be prepared in accordance with the processes indicated above the 0.05:1, the 0.111, the 0.5 :1, and the 1:1 weight ratio copolyrners of monomeric dioctadecenyldimethylammoniurn, -octadecenyldirnethylethylammonium, octadecenyltrimethylammonium, lauryltr-imethylammonium, distearyldimethylam= monium, :dilauryldimethylammoniurn, dihexadecyldimeth-' ylammonium, hexadecyltrimethylammonium, \octadecyltrimethylammonium, laurylbenzyldimethylammoniurn, lauryld'imethyl(ethylhenzyl)ammonium, and laury-l (rnethylenzyl)dimethylarnrnonium acrylates and methacrylates', and monomeric n-octyl, lauryl, oxo-octyl, Z-ethylhexyl, oxo-tridecyl, and n-hexadecyl acrylates and methacrylates.

The detergen-cy characteristics, as Well as the viscosity and visc-osity index improving properties, and the bearing corrosion inhibiting properties of the copolymers of this invention have been demonstrated by preparation and testing of various lubricating oil samples containing representative members of the class of copolymers disclosed herein. Thus, there were prepared and tested separate samples of the same lubricating oil employed as a diluent in Examples '1 and II containing, respectively, 3.3, 3.0, 2.0, and 1.0 percent of C-opolymer 1 (-active ingredient) and 5.0, 1.0, and 0.5 percent of Copolymer 2 (active ingredient). The resulting test samples were examined for viscosity at various temperatures and the viscosity index and pour point of the test samples was measured. Each of the test samples was also subjected to a test adapted to evaluate the detergency characteristics of the test sample. Briefly, in accordance with this test, the oil sample to be tested, preheated to a temperature of about to F. .in a reservoir provided with a heating means and an oil splashing means comprising a number of stainless steel Wires attached to a rotatable steel shaft, is splashed on the surface of a prepolished and tared aluminum test panel heated to a temperature of 500 F. Air is introduced into the oil reservoir at the rate of 10 liters per hour for the eight-hour test period. At the conclusion of the test, the panel is removed and allowed to drain and cool. After cooling, the test panel is washed free from oil, dried and reweighed. The increase in Weight of the panel in milligrams is recorded.

The test sample containing 5 percent of C'opolymer 2 Was tested for bearing corrosion inhibiting properties by employing the oil in a crankcase of a single-cylinder Lauson diesel engine operated under 3 hp load at 1,860 r.p.-m., while maintaining a cooling jacket temperature of 300 F., a crankcase temperature of 225 R, and an airzfuel ratio of 13:1. After 24 hours operation under these conditions, the engine was stopped, dis-assembled, and the copper-lead bearing weight loss was determined.

vThe makeup of the test samples and the results of the above-described tests were as indicated in the following table:

TABLE A Blank l 2 3 4 5 6 7 Test Sample Make-up, Percent by Wt.Hydrogenated SAE 20W/30 Oil Base 10 96. 7 97.0 98. 0 99. 0 95.0 99.0 99. 5 Additives, percent by Wt.,

Active Ingredient:

Copolymer 1, 66.7% Concentrate 3. 3 3.0 2.0 1. 0 Copolymer 2, 47% Con- V centrate 5.0 1. 0 O. 5 Inspections:

Viscosity, SUV: Sec.

(ASTM D446-53) 100 436 v 644 540 494 462 867 520 453 210 F G5. 0 89.3 77.5 72.3 68.6 116 76. 4 67.9 Viscosity Index (ASTM D567-5 117 130 127 124 121 132 128 121 P ;1)157Po7int: F. (ASTM +5 +15 +20 5 5 1 15 0 +5 +5 Dctergency Test: Deposit Wt.,

M 27.0 7.1 8. 7 17.1 12. 5 5.8 7. 5 12.5 Bearing Corrosion Test, Average (lo-Pb;

Bearing Wt. Loss, g 0.855 0. 099

1! Average of eight results.

From the foregoing test results, it will be seen that the copolymers of the present invention impart a marked improvement in the viscosity and viscosity index of the test oils containing the same. In the case of Copolymer 2, a reduction in the pour point of the base oil was also obtained. As also demonstrated by the test results a marked improvement in the detergency characteristics of the oil and a marked reduction in bearing corrosion are obtained by the use of the copolymers described herein.

Test samples of a highly refined, highly paraifinic SAE W lubricating oil were also made up containing, respectively, 3.0 percent of Copolymers 3 and 4. These test samples were examined for viscosity, viscosity-index, color, and pour point. An oil sample containing Copolymer 3 was also subjected to a detergency test in accorddisclosed herein. For example, there can be substituted With good results the 0.05:1, the 0.121, the 0.511, and the 1:1 weight ratio copolymers of (a) a monomeric dioctadecenyldimethylammonium, laur ltrimethylammonium, distearyldimethylammonium, dilauryldimethylammonium, dihexadecyldimethylammonium, laurylbenzyldimethylammonium, lauryldimethyl(ethylbenzyl)ammonium, lauryl (methylbenzyl)dimethylammonium, hexadecyltrimethylammonium, and tristearylmethylammoniurn acrylates or methacrylates and (b) monomeric n-octyl, lauryl, oxooctyl, 2-ethylhexyl, oxo-trirlecyl and n-hexadecyl acrylates or methacrylates.

To the lubricant compositions of the present invention there can be added one or more other addition agents adapted to improve the compositions in one or more reance with the standard FL-2 test procedure. Briefly, in spects. For example, there can be added to the lubricant accordance with the test procedure followed, a standard, compositions of this invention oxidation inhibitors, pour six-cylinder, automotive-type engine is operated for 40 point depressants, soa thickeners, extreme pressure agents, hours subsequent to a one-hour warmup period at conantiwear agents, rust inhibitors, other viscosity index imstant speed and load. Performance of the test oil is provers, other detergents, and the like. Although the injudged by examination of engine parts for deposits. In vention has been described particularly with reference to testing lubricating oils by this procedure a fuel that tends lubricating oil compositions, it will be understood that to promote engine deposits is used. At the conclusion of other lubricating oil compositions such as greases, are the test period, the engine is disassembled and the pistons included by the invention. are examined and rated on the basis of varnish deposits. Numerous modifications and variations of the inven- The internal engine parts are also given a total varnish tion as herein set forth can be resorted to without departrating and a total sludge rating. Each of the above-ining from the spirit or scope of the invention. Accorddicated ratings is then combined in a weighted average ingly, only such limitations should be imposed as are into form a total engine cleaniness rating, a rating of 100 dicated in the claims appended hereto. being considered perfect. In this test the test sample also We claim: contained 0.85 percent by weight zinc-calcium dioctyldi- 1. An oil-soluble copolymer having a molecular Weight thiophosphate, 0.5 percent of a commercial, polymethwithin the range of about 2,000 to about 500,000 obtained acrylate viscosity index improvement agent (Acryloid by copolymerizing in the presence of a free-radical cata- 618) and 0.0003 percent of a commercial polymethyllyst (a) a monomeric alkyl ester of an acid selected from siloxane foam inhibitor (DC Fluid 200), none of which is the group consisting of acrylic and methacrylic acids, and considered to affect detergency under the test conditions Whose alkyl ester substituent contains 8 to 18 carbon employed. The results of the above-described tests Were atoms, and (b) a monomeric quaternary ammonium salt as indicated in the following table: of an acid selected from the group consisting of acrylic TABLE B BlankA BlankB Blank o 1 2 3 Test Sample Make-up, Percent by We;

SAE 10W on Base A 100 97. 0 SAE row on Base 13.. 100 97. 0 SAE 10W on Base 0 100 95.65

Additives, Percent by Wt., Ae-

tive Material:

Copolymer 3 (33.3% in Oil). Copolymer 4 (33.3% in Oil) Zn-Ca Dioctyldithiophosphate Acryloid 618 Polymethylsiloxane (Added). Inspections:

Viscosity, SUV: Sec.

(ASTM D44653) 100 F 155 147 149 232 210 F 44. 2 43. 5 43. 7 5'1. 9 Viscosity Index (AS'IM D567-53 112 111 111 142 Pour Point: F. (ASTM D9757 15 10 10 20 Color: (ASTM Union,

Chevrolet FL-2 Test:

Total Engine Cleanliness Rating Numbers Improvement in Total Engine Rating Compared to Uninhibited Base Oil From the results presented in the foregoing Table B, it will be seen that the copolymers of the present invention effect a marked improvement in the viscosity, viscosity index, pour point, and in some instances, the color of hydrocarbon lubricating oils, and that such copolymers also improve the detergency characteristics of such oils.

The specific embodiments set forth above are illustrative only, and similar results can be obtained by substitu tion in the oil compositions of the preceding embodiments of equivalent proportions of other copolymers of the class and methacrylic acids, one of whose covalent N-bonds is attached to a member selected from the group consisting of monovalent aliphatic hydrocarbon radicals containing 8 to 18 carbon atoms, two other of whose covalent N- bonds are attached to members selected from the group consisting of monovalent aliphatic hydrocarbon radicals containing 1 to 18 carbon atoms, and aralkyl radicals containing 7 to 23 carbon atoms, and Whose remaining covalent N-bond is attached to an alkyl radical containing 1 to 4 carbon atoms, said monomeric quaternary am- 1 1 monium salt and said monomeric alkyl ester being copolymerized when both monomers are in the presence of each other at the same time in a Weight ratio in the range of about 0.03:1 to 1:1.

2. The copolymer of claim 1 Where two of the covalent N-bonds are attached to monovalent aliphatic hydrocarbon radicals containing 12 to 18 carbon atoms and the remaining covalent N-bonds are attached to alkyl radicals containing 1 to 4 carbon. atoms.

3. The copolymer of claim 1 Where two of the covalent N-bonds are attached to monovalent aliphatic hydrocarbon radicals derived from tallow fatty acids and the remaining two covalent N-bonds are attached to methyl groups.

4. The copolymer of claim 1 where one of the covalent N-bonds is attached to a monovalent aliphatic hydrocarbon radical containing 12 to 18 carbon atoms and the remaining covalent N-bonds are alkyl groups containing 1 to 4 carbon atoms.

5. The copolymer of claim 1 where one of the covalent N-bonds is attached to a monovalent aliphatic hydrocarbon radical derived from soya fatty acids and the remaining covalent N-bonds are attached to methyl radicals.

6. The copolymer of claim 1 where three of the covalent N-bonds are attached to monovalent aliphatic hydrocarbon radicals containing 8 to 18 carbon atoms, and the remaining covalent N-oond is attached to an alkyl radical containing 1 to 4 carbon atoms.

7. The copolymer of claim 1 Where three of the covalent N-bonds are attached to caprylyl and decyl radicals and the remaining covalent N-bond is attached to a methyl radical.

8. The copolymer of claim 1 where one of the covalent N-bonds is attached to a monovalent aliphatic hydrocarbon radical containing 8 to 18 carbon atoms, another covalent N-bond is attached to an aralkyl radical containing 7 to 23 carbon atoms, and the remaining covalent N-bonds are attached to alkyl radicals containing 1 to 4 carbon atoms.

9. The copolymer of claim 1 where one of the covalent N-bonds is attached to the monovalent aliphatic hydrocarbon radical derived from coconut oil fatty acids, another of the covalent N-bonds is attached to a benzyl radical, and the remaining covalent N-bonds are attached to methyl radicals.

10. An oil-soluble copolymer having a molecular Weight within the range of about 2,000 to about 500,000

obtained by copolymerizing in the presence of a freeradical catalyst about to 57 percent by Weight of a monomer having the general formula: CH =CRCOOR where R is a member selected from the group consisting of hydrogen and methyl, and R is an alkyl group containing 12 to 18 carbon atoms, and about 5 to 43 percent of a monomer having the general formula:

CH2=CROO ON R/ll where R is as defined above, R is a member selected from the group consisting of alkyl, alkenyl, and alkadienyl radicals containing 12 to 18 carbon atoms, R" and R are members selected from the group consisting of alkyl radicals containing 1 to 18 carbon atoms, alkyl and alkadienyl radicals containing 8 to 18 carbon atoms and aralkyl radicals containing 7 to 23 carbon atoms, and R"" is an alkyl radical containing 1 to 4 carbon atoms, said monomers being copolymerized when both monomers are in the presence of each other at the same time.

11. The copolymer of claim 10 where the nitrogen content of the copolymer is in the range of about 0.04 to 3.0 percent by Weight of the copolymer.

References Cited by the Examiner UNITED STATES PATENTS 2,104,796 1/1938 Dietrich 25234 2,430,951 11/1947 Rouault 25234 2,435,777 2/1948 Glavis et al. 26086.1 XR 2,737,496 3/1956 Catlin 260-86.1 2,741,568 4/1956 Hayek 2602.1 2,830,021 4/1958 Smith et a1 25234 2,843,573 7/1958 Melamed 260861 2,892,822 6/1959 Gray et a1. 26086.1

OTHER REFERENCES The Condensed Chemical Dictionary, 5th edition, 1956, Reinhold Publishing Corporation, New York, pages 18 and 19 pertinent.

JOSEPH L. SCHOFER, Primary Examiner.

JULIUS GREENWALD, PHILIP E. MANGAN,

DONALD CZAJA, JAMES A. SEIDLECK,

Examiners. 

1. AN OIL-SOLUBLE COPOLYMER HAVING A MOLECULAR WEIGHT WITHIN THE RANGE OF ABOUT 2,000 TO ABOUT 500,000 OBTAINED BY COPOLYMERIZING IN THE PRESENCE OF A FREE-RADICAL CATALYST (A) A MONOMERIC ALKYL ESTER OF AN ACID SELECTED FROM THE GROUP CONSISTING OF ACRYLIC AND METHACRYLIC ACIDS, AND WHOSE ALKYL ESTER SUBSTITUENT CONTAINS 8 TO 18 CARBON ATOMS, AND (B) A MONOMERIC QUATERNARY AMMONIUM SALT OF AN ACID SELECTED FROM THE GROUP CONSISTING O FACRYLIC AND METHACRYLIC ACIDS, ONE OF WHOSE COVALENT N-BONDS IS ATTACHED TO A MEMBER SELECTED FROM THE GROUP CONSISTING OF MONOVALENT ALIPHATIC HYDROCARBON RADICALS CONTAINING 8 TO 18 CARBON ATOMS, TWO OTHER OF WHOSE COVALENT NBONDS ARE ATTACHED TO MEMBERS SELECTED FROM THE GROUP CONSISTING OF MONOVALENT ALIPHATIC HYDROCARBON RADICALS CONTAINING 1 TO 18 CARBON ATOMS, AND ARALKYL RADICALS CONTAINING 7 TO 23 CARBON ATOMS, AND WHOSE REMAINING COVALENT N-BOND IS ATTACHED TO AN ALKYL RADICAL CONTAINING 1 TO 4 CARBON ATOMS, SAID MONOMERIC QUATERNARY AMMONIUM SALT AND SAID MONOMERIC ALKYL ESTER BEING COPOLYMERIZED WHEN BOTH MONOMERS ARE IN THE PRESENCE OF EACH OTHER AT THE SAME TIME IN A WEIGHT RATIO IN THE RANGE OF ABOUT 0.03:1 TO 1:1. 